I've just replaced the clutch and flywheel on a 308 that someone else has built. The engine is modified, probably a cam, headers, seems to have blue heads on a red block - you get the idea.
The clutch failed because it was worn out. There was no major failure, the shift just became notchy, wouldn't take reverse. It's a Supra 5spd which has been going very well.
The old flywheel was lightened so it had cracked. Replacement flywheel is standard, I've had it balanced (no change needed) and then the new pressure plate balanced with the flywheel by reputable machine shop in Perth.
Now has a vibration that increases from minor at low speeds to worst at about 2000 rpm and then drops away by about 3000 rpm, so it seems taking the old flywheel off has disturbed something on the motor.
The harmonic balancer doesn’t look standard to me – very heavy rim around the outside. Was this somehow matched to the lightened flywheel that I have taken off? I will replace it and see how that affects the behaviour.
Any ideas would be much appreciated.

It could have been balanced with weight added to or subtracted on the old flywheel. It could also be a 377 stroker using a 400 crank or a COME crank, meaning the flywhhel needs to have weight added. Easiest way to fix it is to get the balance of the old f

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Thanks Byron. On the old wheel, added weight would be pretty obvious wouldn't it? There's nothing obvious added, just half the metal machined out of the rim and a lot tak

Im getting the impression this ute is a bit wasted on me. Must be why its good to drive.